3.3 Proteins and Nucleic Acids

Vocabulary flashcards based on lecture slides covering protein functions, amino acid structure, peptide bonds, dehydration and hydrolysis reactions, denaturation, and the four levels of protein structure.

Protein

A biological macromolecule that performs many functions including support, metabolism, transport, defense, regulation, and motion, and is composed of amino acid monomers.

Amino Acid

The monomer of proteins, consisting of a central carbon bonded to a hydrogen atom, amino group, carboxyl group, and a side chain, or R group.

R Group

The side chain attached to the central carbon of an amino acid that varies across the $20$ different amino acids and causes them to differ from one another.

Peptide

Two or more amino acids covalently linked together.

Peptide Bond

A covalent bond formed by a dehydration reaction between two amino acid monomers.

Polypeptide

A chain of many amino acids joined together by peptide bonds.

Amino Acid Sequence

The order of amino acids in a polypeptide chain that determines the final three-dimensional shape of a protein.

Dehydration Synthesis Reaction

A reaction between two amino acid monomers that forms a peptide bond and produces a molecule of $H_2O$.

Hydrolysis Reaction

A reaction that breaks down a peptide bond using a molecule of $H_2O$.

Denaturation

The loss of structure and function in a protein, usually caused by changes in pH or temperature.

Primary Structure

The first level of protein organization, defined as the sequence of amino acids.

Secondary Structure

The level of protein organization where portions of the chain form helices (such as an alpha helix) or pleated sheets.

Tertiary Structure

The overall three-dimensional globular shape resulting from interacting secondary structures.

Quaternary Structure

The level of protein organization formed when more than one polypeptide chain is interacting.